fix: improve /openDevContainer support with local workspace folder

This change allows `localWorkspaceFolder` and `localConfigFile` to be
provided which allows us to use `dev-container` rather than
`attached-container` to enter enabling all dev container features like
file change detection and rebuilding.

Author: mafredri

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## Unreleased
 
+- Update `/openDevContainer` to support all dev container features when hostPath
+  and configFile are provided.
+
 ## [v1.9.2](https://github.com/coder/vscode-coder/releases/tag/v1.9.2) 2025-06-25
 
 ### Fixed

src/commands.ts

@@ -631,6 +631,8 @@ export class Commands {
 		const workspaceAgent = args[2] as string;
 		const devContainerName = args[3] as string;
 		const devContainerFolder = args[4] as string;
+		const localWorkspaceFolder = args[5] as string | undefined;
+		const localConfigFile = args[6] as string | undefined;
 
 		await openDevContainer(
 			baseUrl,
@@ -639,6 +641,8 @@ export class Commands {
 			workspaceAgent,
 			devContainerName,
 			devContainerFolder,
+			localWorkspaceFolder,
+			localConfigFile,
 		);
 	}
 
@@ -751,6 +755,8 @@ async function openDevContainer(
 	workspaceAgent: string,
 	devContainerName: string,
 	devContainerFolder: string,
+	localWorkspaceFolder: string | undefined,
+	localConfigFile: string | undefined,
 ) {
 	const remoteAuthority = toRemoteAuthority(
 		baseUrl,
@@ -759,11 +765,28 @@ async function openDevContainer(
 		workspaceAgent,
 	);
 
+	if (!localWorkspaceFolder) {
+		localConfigFile = undefined;
+	}
+	let configFile;
+	if (localConfigFile) {
+		configFile = {
+			path: localConfigFile,
+			scheme: "vscode-fileHost",
+		};
+	}
 	const devContainer = Buffer.from(
-		JSON.stringify({ containerName: devContainerName }),
+		JSON.stringify({
+			containerName: devContainerName,
+			hostPath: localWorkspaceFolder,
+			configFile,
+			localDocker: false,
+		}),
 		"utf-8",
 	).toString("hex");
-	const devContainerAuthority = `attached-container+${devContainer}@${remoteAuthority}`;
+
+	const type = !!localWorkspaceFolder ? "dev-container" : "attached-container";
+	const devContainerAuthority = `${type}+${devContainer}@${remoteAuthority}`;
 
 	let newWindow = true;
 	if (!vscode.workspace.workspaceFolders?.length) {

src/extension.ts

@@ -165,6 +165,8 @@ export async function activate(ctx: vscode.ExtensionContext): Promise<void> {
 				const workspaceAgent = params.get("agent");
 				const devContainerName = params.get("devContainerName");
 				const devContainerFolder = params.get("devContainerFolder");
+				const localWorkspaceFolder = params.get("localWorkspaceFolder");
+				const localConfigFile = params.get("localConfigFile");
 
 				if (!workspaceOwner) {
 					throw new Error(
@@ -190,6 +192,12 @@ export async function activate(ctx: vscode.ExtensionContext): Promise<void> {
 					);
 				}
 
+				if (localConfigFile && !localWorkspaceFolder) {
+					throw new Error(
+						"local workspace folder must be specified as a query parameter if local config file is provided",
+					);
+				}
+
 				// We are not guaranteed that the URL we currently have is for the URL
 				// this workspace belongs to, or that we even have a URL at all (the
 				// queries will default to localhost) so ask for it if missing.
@@ -228,6 +236,8 @@ export async function activate(ctx: vscode.ExtensionContext): Promise<void> {
 					workspaceAgent,
 					devContainerName,
 					devContainerFolder,
+					localWorkspaceFolder,
+					localConfigFile,
 				);
 			} else {
 				throw new Error(`Unknown path ${uri.path}`);